Genes

Understanding Genes

• Genes are sections of DNA that control the development of different characteristics in living organisms.
• They are located on long molecules of DNA called chromosomes, present in the nucleus of every cell.
• Each gene carries instructions for making a specific protein, which then builds specific traits.
• Humans have approximately 20,000-25,000 genes in their genome.
• Genes are made up of four different types of nucleotides, symbolised by the letters A, T, C, and G.
• Pairs of genes, one from each parent, form alignments called alleles.

Genetic Traits and Variation

• Genes decide the characteristics of an organism through the presence of dominant and recessive alleles.
• A trait determined by a dominant allele will always show in the organism even when paired with a recessive allele.
• For a recessive trait to be visible, an organism must have two copies of the recessive allele, one from each parent.
• Variations in traits could be a result of environmental influences, mutations, or, most commonly, the combination of genes from both parents.

Genetic Disorders and Mutations

• Defects or changes in genes can lead to genetic disorders.
• Mutations are alterations in the DNA sequence that make up a gene.
• These changes could be beneficial, neutral, or deleterious, influencing the organism’s survival and reproduction abilities.
• Mutations are the primary source of genetic variation, which is crucial for evolution to occur.

DNA and Genetic Engineering

• DNA technology allows scientists to manipulate gene sequences, creating genetically modified organisms (GMOs).
• This is fundamental in various fields, such as medicine, where diseases can potentially be treated or prevented by gene therapy.
• Scientists can also utilise genetic engineering in agriculture to develop crops that are more resistant to pests, disease, or harsh weather conditions.